Fix _signal_handler call by signal.signal

[SnipGhost]

The stack_frame was removed in the commit, however this resulted in an error on exiting:

TypeError: _signal_handler() takes 2 positional arguments but 3 were given

As the signal.signal() is expecting a callback function with 2 arguments (self + signum & frame)

handler can be a callable Python object taking two arguments (see below), or one of the special values signal.SIG_IGN or signal.SIG_DFL.